U.S. Patent Application No. 2002/0186214A1 by Siwinski et al., published Dec. 12, 2002, shows a method for saving power in an organic light emitting diode (OLED) display having pixels comprised of red, green, blue and white light emitting elements. The white light emitting elements are more efficient than the other colored light emitting elements and are employed to reduce the power requirements of the display.
While power efficiency is always desirable, it is particularly desirable in portable applications because an inefficient display limits the time the device can be used before the power source is recharged. In fact, for certain applications the rate of power consumption may be more important than any other display characteristic with the exception of visibility. Referring to FIG. 2, an arrangement of four pixels 10 having red 12, green 14, blue 16 and white 18 light emitting elements as taught by Siwinski is shown. The light emitting elements in each pixel are arranged in a two by two array.
Widely used text rendering software such as Microsoft ClearType™ relies upon displays in which the colored elements of the display are arranged to form vertical stripes. Such arrangements are known in LCD displays that have pixels comprised of red, green, and blue light emitting elements. An example of such an arrangement is shown in FIG. 3, however this arrangement does not provide the power savings of the display device taught by Siwinski.
There is a need, therefore, for an improved full-color flat-panel OLED display having improved power efficiency while maintaining full-color reproduction and compatibility with a stripe-pattern arrangement.